Monopole

From http://en.wikipedia.org/wiki/Magnetic_monopole:
a) The extended Maxwell's equations would be fully symmetric equations if one allows for the possibility of "magnetic charges" analogous to electric charges.

b) The presence of electric charge was simply "inserted" into quantum mechanics (QM), but in 1931 Dirac showed that a discrete charge naturally "falls out" of QM ... The hypothetical existence of a magnetic monopole would imply that the electric charge must be quantized in certain units; also, the existence of the electric charges implies that the magnetic charges of the hypothetical magnetic monopoles, if they exist, must be quantized in units inversely proportional to the elementary electric charge.

A number of attempts have been made to detect magnetic monopoles. ... there have been tantalizing events recorded, in particular the event recorded by Blas Cabrera on the night of February 14, 1982 (thus, sometimes referred to as the "Valentine's Day Monopole"):
First Results from a Superconductive Detector for Moving Magnetic Monopoles. by Blas Cabrera Digital Object Identifier doi:10.1103/PhysRevLett.48.1378

Journal reference: Physical Review Letters 48 (20): 1378-1381.

Yet until now there has never been reproducible evidence for the existence of magnetic monopoles.Magnetic Monopole Searcheslecture notes by G. Giacomelli, L. Patrizii

Experimental searches with liquid scintillator system are described in chapters 2.1.1, 2.1.2, 2.4 for monopoles of different velocities.
Theoretical and Experimental Status of Magnetic Monopolesreviewed recently by Kimball A. Milton